1. Field of the Invention
The present invention relates to an intelligent network (IN) and, more particularly, to a method of processing an intelligent network application protocol (INAP) for communication between a service switching point (SSP) of an intelligent network and a transaction capabilities application part (TCAP).
2. Description of the Related Art
Since 1836, when the telephone was invented, it has been dramatically developed both technically and quantitatively. However, in the middle of 1980 the telephone confronted several changes. First, the number of new telephone subscribers has decreased, second, the consciousness of the subscribers has changed and third, a competitive principle was introduced to the communication market. To correspond to the above changes, service providers have added a computer for controlling a service and database for executing the service on a conventional telephone network, thereby providing various services instantly by using the newly added computer and database in addition to transferring information through the conventional telephone network. Gradually, the above changes were dealt with by an intelligent network (IN) which combines a computer network to the telephone network in a method of No. 7 common channel signaling, and separates into two functions of simply connecting a telephone call and controlling the service hierarchically, thereby creating and controlling new services rapidly and efficiently.
FIG. 1 shows the structure of the initial IN. As shown in FIG. 1, the IN includes a service control point (SCP) which has the communication service controlling logic in the network; a service management system (SMS) for managing data required for providing the service; a service switching point (SSP) for connecting the SCP to the conventional local exchanger; and a No. 7 common channel signaling system. The SCP includes a specific type of electronic switching system or a common computer and the SSP includes the specific type of electronic switching system for connecting to service users. The SSP includes IP, which receives the request signal of specific information and provides the resources. A new protocol for objectifying common functions, which do not depend on certain services and re-performing the common functions is required in the IN for the next generation. Therefore, ITU-T (International Telecommunication Union-Telecommunication standardization section) recommends INAP for interactions among the intelligent network components to satisfy above requirements. The INAP is an application layer protocol for supporting interactions among physical subjects and No. 7 common channel signaling system is mainly used as a lower protocol of the INAP.
FIG. 2 shows the structure of a multi-protocol performed when a service switching point (SSP) and a service control point (SCP) exchange an INAP operation with a TCAP message through the No. 7 common channel signaling system. A message transmit protocol (MTP) is divided into 3 stages of MTP level 1, MTP level 2, MTP level 3. Electrical, physical and functional characteristics are prescribed at the MTP level 1, and at the MTP level 2, error detecting and correcting, error monitoring of order message and signal link is performed in order to transmit a reliable signal message between two signal points. MTP level 3 defines the common transmission function and procedure used for independent operation of an individual signal data link and at the same time manages the signal network for maintaining the normal message processing according to the signal network state. A signaling connection control part (SCCP) takes charge of transmission of signal data and execution of logical signaling connection control in a network together with the MTP. In addition, the TCAP performs a function for providing connectionless intelligent network service among elements of the communication network, and the INAP supports interactions among physical subjects.
However, the ITU-T proposed only general recommendations with respect to the INAP and TCAP that exchange the INAP operation but did not suggest a concrete method for processing messages between the INAP and TCAP.